Micro lab midterm Flashcards

Terms Definitions
2 purines
adenine, guanine
Respiration or fermentation? carbon atoms of organic compounds are only partially oxidized.
The photoreactivation method of thymine dimer repair uses ___ energy.
intracellular enzyme possessed by bacteria that hydrolyzes lactose into beta-glucose and beta-galactose
T/F - heat is a disinfectant
differential media
differentiate betwen pathogenic and non-psthogenic bacteria
In respiration, ATP is prodcued through ____.
Oxidative phosphorylation
What organisms can be distinguished with the MR test?
enteric organisms
A chemical agent used on inanimate objects to destroy microorganisms
organisms which live together in a particular environment
The ___ test indicates fermentation of glucose to 2,3-butandiol and ethanol.
Voges-Proskauer (VP)
The Oxidase test determines if organisms have ____.
Cyt C oxidase
The acid:alcohol ratio in the MR test is relatively ___.
Group __ strep is the only group resistant to salt
2 enzymes that are involved in nitrogen fixation
nitrogenase, transaminases
3 Tests that test for metabolic intermediates or end-products.
Indole, MR, VP
What kind of bacteria can survive in the presence of oxygen but won't use it for metabolism?
Aerotolerant anaerobes
What indicator is used for the urease test?
phenol red
Methods to evaluate effectiveness of chemical agents.
Phenol coefficient and use-dilution
____ play a role in the virulence of the pathogenic organisms by aiding the infecting organism to escape some of the hosts protective mechanisms. Results in the organism being able to spread to the bloodstream.
What does yellow color formation in the ONPG test indicate?
organism produces beta-galactosidase
Medium used for cysteine desulfurase test?
Klinger's iron agar (KIA slant)
Positive result for the cysteine desulfurase test.
dark precipitate indicates H2S production :: yellow = positive fermentation
Counts all cells alive and dead, using a hemocytometer
direct microscopic count
2 diseases caused by e. coli
infant diarrhea and montezuma's revenge
In the catalase test, Catalase converts ___ to __ and ___.
hydrogen peroxide to H2O and O2
Which produces more energy? oxidative phosphorylation or substrate level phosphorylation
oxidative - therefore, those colonies on top of agar grow better than those within agar
__ test is used to identify group d strep
bile esculin hydrolysis
what type of stains work on bacteria? what is methylene blue?
cationic or basic dyes(bact.neg.charged) methylene chloride
What do the dyes in EMB do?
inhibit growth of Gram-positive organisms & produce dark medium and sheen that indicates large acid production
What dye is used in the oxidase test and why?
p-phenylenediamine dihydrochloride - forms dark blue color if cyt c is present
What is the Bergey's manual and how is it useful in the identification process?
classification system of bacteria
Explain streak plate isolation. What is the drawback?
1. Streak plate isolation. Divide into 3 sections, flame loop between each new area. Only good for aerobic bacteria.
Positive result for oxidase test
If the dye is reduced, it turns a blue/black color
4 ways to distinguish strep from staph
strep cells arranged in chains or pairs and are smaller and elongated, colonies exposed to air are diff, catalase not produced in strep, staph can tolerate salt
How do you distinguish late lactose fermenters from nonfermenters?
by ONPG, which can enter bacteria without aid of permease and is similar to beta-lactose, so can act as a substrate for any beta-galactosidase present
Phenol red is yellow at what pH? red at what pH? pink at what pH?
-yellow below 6.8-red between 7.4-8.4-pink at 8.4 and above
What assumption is the standard plate count based on?
That each colony arose from a single bacterium.
What type of bacteria is often a sign of utensil sanitation issues in milk production? what is unique about these organisms?
thermoduric bacteria, survive, but do not grow, at pasteurization temperature. affect shelf life
What does good growth in endo agar mean?
-organism is not inhibited by sodium sulfite or basic fuchsin-organism is gram-negative
How are the results of the cysteine desulferase test interpreted?
a dark precipitate = pos for H2S production
What does no clearing around growth on the starch agar indicate?
no amylase is present, no starch was hydrolyzed by bacteria
no growth
What is coagulase?
slightly curved rods
solid media
1.5% agar
vancomycin resistant staph aureus/enterococcus
extreme thermophile
80 - 121C
inhibits growth of eukaryotic organisms and molds but not streptomyces, antibiotics can be isolated from soil with addition of cyclohexamide
Saccharomyces cerevisiae
gram-negative. fungi. dimorphic. cocci-oval/elongated shape. reproduces by budding which you will most likely see- asexual, similar to binary fission but gets to unequal cells- budding yeast.
Proteus vulgaris
gram- negative. bacilli- rod.
entire (smooth, no irregularites), undulate (wavy), lobate (lobed), filamentous, or rhizoid (branched like roots)
color bearing ions in dyes
an organism, not normally pathogentic, taking advantage of a compromised host
process by which organisms produce proteo
streptomyces produce
over 2/3 clinically useful antibiotics
quantitative, confirmed test, completed test, and identification using Enterotube II.
study water analysis!
doesn't matter- live throughout the media
basic stains
auxochrome becomes positively charged- they are attracted to the negative charges on the surface of most bacterial cells. *methylene blue, crystal violet, and safranin
Fluid thioglycollate medium tests for ___________ microbes.
+/- bacitracin
+ strep pyogenes- strep agalactiae
unicellular fungi. Pseudohyphae. replicate by budding (instead of binary fission).
staphylococcus epidermidis
pathogenic on wounds, catheters and heart valves
agar media
solidifying agent used to physically, not nutritionally, support bacterial growth. 
physical removal of germs. reduces the total microbial load. some examples- soap, detergents, alcohol
aerotolerant aerobes
respire anaerobically even when oxygen is present
_________ alcohol is used to rinse away unbound dye and to __________ Gram negative cells.
area including sites outside the host where microbe resides and serves as a poential source of infection
acid-fast organisms contain what?
mycolic acid, a lipid
prokaryotic cell components
nucleiod, cell membrane, ribosomes, cell wall, periplasm (gram - only), outermembrane (gram 0 only), capsule, flagella
Gram stain
not a routine procedure, but can visualize Candida and Cryptococcus
Pityrosporum ovale
responsible for dandruff when in large numbers
media for resp flora
blood agar, mannitol salt plate
obligate anaerobes
cannot grow with oxygen- inhibit the lower 2/3 of media
a visible clump of growth on the surface of the agar
A counter stain, _________ is used to stain Gram ________ bacteria pink.
Which bacteria was not inhibited by desoxycholate, but did not ferment?
Salmonella typhimurium
Define: Malt, Mash, Wort
Malt: Geminated barley cornsMash: Liquid and barleyWort: Sugar water
Colonies of growth that all run together.
Confluent growth
Gram -
thin peptidoglycan. outer membrane. stain pink
What is the treatment of Rocky Mt spotted fever?
Tetracycline orChloramphenicol
What gives the CFU
colonies which grow in conjunction with the used dilution factor.
semisolid media
see if bacteria is motile or not. *used for medical specimens containing bacteria
Agar deep stabs are used to test for ______________.
Normal Flora of the nose
Staph epididimous, Staph aurus, diptheroids
Difference between differential staining and simple staining
Simple Staining Technique:
Use of a single dye
Determines cell morphology, size, and arrangement
Differntial staining:
two dyes
determines the difference between 2 organisms
long threads that make mold. Can be septate (compartments) or aseptate (no compartmetns)
How would you differentiate Streptococcus pneumoniae from normal respiratory alpha streptococci?
Leading cause of pneumoniae, otits media, and meningitis.
pathogenic species of flora of throat and nasal passages
Staphylococcus aureus, corynebacterium diptheriae, neisseria meningitides, haemiophilus influenzae
Eosin Methylene Blue Agar
Tolerance to eosin and MB dyeLactose and sucrose fermenta.Acid production
examples of differential stains?
gram, acid fast, capsule, spores or flagella
Antibiotic test is qualitative or quantitiave?
Qualitative-don't know med. thickness etc.
2 reasons gram staining is a differential staining technique
two dyes
differentiates between groups of bacteria
Brain-heart infusion agar w/ 5% blood
supports the growth of dimorphic fungi
zone of inhibition
a halo which has formed around a disk which contains various chemicals due to the death or inhibition of bacterial cells. (bacteriocidal agents will also form zones of inhibition)
oil immersion steps
high power, in focus- drop a drop of oil directly on smear, then rotate to oil immersion lens
Lab 18State the difference between a qualitative serological test and a quantitative serological test.
Qualitative test only determines whether the antibodies are present and is used for screening purposes. Quantitative test give the titer or amount of the antibody in the serum and is used to moniter progress of a disease.
Name and describe the 3 different hemolysis types
Beta H - complete lysis-transparent.Alpha H - Greenish discolorationGamma H - Absence of visible change
What are the three structural components of a virus?
1. Nucleic Acid core-DNA or RNA2. Capsid3. Envelope
Lab 18Interpret the results of the following serological tests: a. serologic test for infectious mononucleosisb. serologic test for SLEc. FTA-ABS test
a. Positive will show agglutination of horse erythrocytes.b. Positive will show cluping a DNA attached to latex (for visibility) by anti-deoxyribonucleoprotein.c. Positive reaction will show florescing spirochetes because antibodies against the Treponema pallidum antibodies have been attached to florescent particles.
Inhibition zone size is depensant on
growth medium, solubility of the ab, rate of diffusion through the medium, sensitivity of the organism, density of inoculum.
How is Rocky mt spotted fever is transmitted?
by animal reservoirs. Bite of arthropod (tick).
Lab 18State the most common reason for a false-negative HIV antibody test.
Usually occur because the patient has been recently infected and has not had time to make sufficiant amounts antibodies to be detected.
How do you find the number of phage particles in the original inoculum?
The number of plaques formed.
Examples of mechanical defense mechanisms
1. Cilia in mucus membranes impedes invasion of microbes 2. Skin epithelial keratin barrier3. Sneezing4. Urine flow
Lab 19State whether or not boiling is an effective means of sterilization, and indicate why.
No, since boiling will not destroy endospores and some viruses can survive extensive boiling.
what is an advantage of the negative simple stain?
cells remain true to their normal size. no heat fixing = no shrinking or distortion
2 reasons why the human throat is an ideal environment for microbial growth to occur?
mucus is a good media, turns over nutrients/waste, large aerobic surface area
short rods
healthy, strong growth
associated w host
positive mannitol fermentation
yellow halo
introduction of unwanted organisms
live in hypertonic enviroments
Pseudomonas aeruginosa
quintessential opportunistic pathogen of humans. invade virtually any tissue. leading cause of hospital acquired (nosocomal) gram-negative infections
survive only in environments containing lower than atmospheric levels of oxygen- grow in the middle
MacConkey Agar
Lactose/fermentable sugar.Brick red for positive fermentation.- no color change
all prokaryotic. diverse enviroments. heterotrophs and photosynthetic. Size 0.5 - 1 micromenter. Shapes: spherical, rods, spiral
Diseases transmitted to humans from animal reservoirs by biteEX: tick transfers Rickettsiae
opportunistic pathogens
strike when opportunity like compromised immune system (candida albicans)
mutation that causes a single nucleotide change, which then leads to a change in the amino acid sequence of a peptide
suface membrane produced by organisms cultivated in broth that float on the top of the medium
Mycobacterium tuberculosis
red, acid-base stain. bacilli-rods. tend to clump together. grows as a very hard, granular colonnade. must include background color even if it's colorless. nonmotile, nonsporing, weakly gram-positive. 
Phenol Ethanol Agar
Tolerance to Phenol Ethanol
+/- 6.5% broth
+ enterococcus fecalis- other
To which streptococcal disease is there a vaccine?
Streptococcus pneumoniae
Saccharamyces cerevisiae
used in baking and fermenting alcoholic beverages. model organism in modern cell biology research, most thoroughly researched eukaryotic organism
Koch's postulates
define a procedure that determines which organism causes a specific disease.
membrane-filter technique
this technique detects presence of much more abundant coliform such as e.coli or e. argoenes.
stained preparations
the preparation applied to dead cells
ENDO agar
media used to detect water contamination. contains color indicators that are grampositive inhibitors. detects lactose fermentors--> selective and differential, for gram negative.
bright field microscopy is the
most commonly used
Optochin and Bacitracin Sensitivity
If alpha/beta hemo.Beta-use becutracinAlpha-use optochin
gram +
Thick peptidoglycan. no outer membrane. stain purple.
Why are Salmonella and Shigella notifiable disease?
Cause notifieable diseases:Salmonella-Typhoid FeverShigella-Bacillary dysentery
urea broth
test for presence of urease (breaks down urea) urease + = red (alkaline)
if you innoculated a nutrient agar slant of Serratia marcescens and left it out over night on your bench, in the morning you would most likely see?
red colonies
liquid form
what is the form of nutrient broth?
What color of bacteria on the MacConkey agar indicates the bacteria is fermenting acid?
Red/pink growth
What are two common acidic stains
nigrosin and eosin
What media is used to differentiate Staph aureus?
Mannitol Salt
Complex media
exact composition unknown. such as beef extract
inhibitory mold agar (IMA)
enriched medium w/ gentamicin or chloramphenicol that supports growth of almost all fungi; inhibits bacteria
What is the difference in a precipitation reaction and an agglutination reaction?
Precipitaion reaction-(invitro),fine cloudy reaction, liquad form in test tube, insolubleAgglutination-coagulation on slide or test tube, soluble
is it high temp or pressure that kills microorganisms
in molds where would you expect to find most of the nutrient uptake occuring?
hyphal tips
water analysis
look for coliforms. it is positive if it produces gas and bubbles up- turbidity.
total magnification is
mag of objective x mag of ocular
What type of media are liquids that either contain nutrients that encourage the growth of desired bacteria or contain inhibitory substances that suppress competition?
Enrichment Broth
acidic dyes (-)
nigrosin and india ink
(bacteria is negative)
(used in negative simple stain)
Periodic Acid-Schiff (PAS) and Gomori's Methenamine Silver (GMS) stains
best for demonstrating fungi in TISSUE
normal flora of skin include
yeasts and bacteria. yeasts primarily Pityrosporum
larger, "typical" colonies
develop on the surface where they are not confined by medium.
Gram ____ bacteria appear purple while Gram ____ bacteria appear pink.
Positive = PurpleNegative = Pink
Actual limit of resolutionD=
wavelength / NA condensor + NA objective
Tryptic Soy Broth (TSB)
Green tube. Add drops of Kovac's reagent. Positive Indole test shows red color.
lysogenic lifecycle
1. attachment to host 2. integrate viral DNA into host's DNA. 3. DNA replication 4. maturation 5. cell lysis
What is the difference between food poisoning and infection?
Food Poisoning-general term for illness contracted by ingesting contaminated foodFood Infection-result of ingesting pathogen-contaminated food.
how is oxygen removed from media
autoclaving, gas packet when mixed with water convert O2 to CO2 and H+ ions
the disk diffusion test
what did we use to test disinfectants and antiseptics?
Lab 19State specifically how moist heat kills microorganisms.
Moist heat kills by denaturing proteins and possibly melting lipids.
Characteristics of Enterobacteriaceae family:
some are normal inhabitants of the GI tract
gram -
non-spore formers
Why are mycoplasmas highly pleomorphic?
Lack of cell wall enables them to alter their shape to fit an animal cell.( via phagocytosis)
Lab 19State why filters are preferred over autoclaving for such materials as vaccines, antibiotic solutions, sera, and enzyme solutions.
It can sterilize solutions like vaccines and vitamins that would be damaged by autoclaving.
What is a positive reaction for a Mannitol Salt Agar test?
Color change in the agar
casein may be metabolized all the way down to
individual amino acids. this process is called peptonization, results in a clear(not milky) liquid that is usually brown in color.
Lab 17Correctly interpret the results of the following serological tests: a. serological typing of Shigella b. serological typing of streptococci c. serological testing for pregnancy
a. Clumping in one of the serology wells indicates a positive reaction with one of the subgroup antibodies.b. Clumping of the latex in the wells indicates a positive for that Lancefield group. c. A red line crossing the blue line indicates a positive; HGC (the hormone being tested for) binds to antibodies along a strip in the test card, other antibodies bound to latex then bind to HGC turning the strip red and indicating a positive.
Two most important properties of Streptococci?
1. The type of hemolysis on blood agar2. The serological specificity of cellular(somatic)ag.
Why did you get different results with E. coli and the Micrococcus luteus in lysozyme experiments?
Microcuccus are G+ and lysed by lysozymeE. coli are G- unaffected
Lab 17Describe the concept and general procedure for using serologic testing to identify unknown antigens (direct serologic testing).
The test is based on the fact that antigen-antibody reactions are very specific (antibodies usually only react with the antigen that stimulated their production). A suspension of unknown antigen is mix with a known antibody and a reaction between them is looked for.
invert it so the condensation won't fall onto the medium before it is set
what do you do to your spread plate before you incubate it?
Lab 20State why the results of an in vitro test to evaluate chemical agents may not necessarily apply to in vivo situations.
The conditions of the in vivo test may vary from the conditions of the in vitro test.
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